1. Field of the Invention
The present invention relates to a threading apparatus for putting a sewing thread through an eye hole of a sewing needle of a sewing machine.
2. Related Art Statement
There is known a threading device of a sewing machine which device includes a supporting member which is movable relative to a sewing needle and which supports a threading hook such that the hook can advance and retract through an eye hole of the needle. After a sewing thread fed to a position adjacent to the needle eye is caught by a notch of the hook advanced through the needle eye, the hook is retracted back through the needle eye. Thus, the sewing thread is put through the needle eye. The known threading device further includes an elastic member which biases the thread against the notch of the hook while the thread put through the needle eye is drawn out to make a thread loop. Thus, the thread put through the needle eye is securely held by the hook and the elastic member. This threading device is disclosed in Unexamined Japanese Patent Application laid open for inspection under Publication No. 3-143486.
The above prior threading device is described in more detail by reference to FIGS. 12(A) to 12(E).
As shown in FIG. 12(A), when a threading unit is located at an initial position thereof, i.e., an uppermost position thereof, a metal wire 186 as an elastic member of the threading unit is engaged with a notch 172a of a threading hook 172 such that the wire 186 is, in an initial state thereof, slightly elastically deformed and accordingly is biased or pressed against the front wall of the notch 172a provided in a tip portion of the hook 172. Subsequently, the threading unit is moved downward, so that an elevation level of the hook 172 is aligned with that of an eye hole 118a of a sewing needle 118, as shown in FIG. 12(B).
Then, a supporting bar (not shown) which extends parallel to a needle bar (not shown) to which the sewing needle 118 is secured, is rotated by a rotating device (not shown), so that the notch 172a of the hook 172 goes through the needle eye 118a, as shown in FIG. 12(C). When the notch 172a advances through the needle eye 118a, the wire 186 is elastically deformed by a stopper member (not shown) to move away from the notch 172a in a horizontal direction, so that the wire 186 is prevented from contacting the needle 118. Accordingly, the notch 172a advanced through the needle eye 118a catches a sewing thread 168 stretched in front of the needle eye 118a. Subsequently, the supporting bar is rotated back, and the hook 172 catching the thread 168 is retracted back through the needle eye 118a to draw the thread 168 through the eye hole 118a and make a loop of the thread 168. During this step, the wire 186 is again biased or pressed against the notch 172a of the hook 172 via the thread 168 being held therebetween. Thus, the thread 168 is securely held by the hook 172 and does not fall off the same 172.
When the threading unit is moved upward as shown in FIG. 12(E), the hook 172 draws the thread 168 through the needle eye 118a to provide a sufficient length or amount of the thread loop 168.
Thus, the prior threading device enjoys the advantage that the thread loop 168 does not fall off the hook 172 when being drawn through the needle eye 118a because the wire 186 as the elastic member biases the thread 168 against the notch 172a of the hook 172. However, since the wire 186 continues to press the thread 168 on the hook notch 172a even after a sufficient length or amount of the loop 168 is drawn through the needle eye 118a, as shown in FIG. 12(E), the prior threading device suffers from the following disadvantages: The thread 168 should finally be released from the hook 172 in order that a user may start sewing operation. To this end, however, the user is required to move the wire 186 in a direction away from the hook notch 172a. For example, the thread 168 should be pulled in a direction indicated at arrow, YD, in FIG. 12(E).
In many sewing machines, a threading hook 172 is moved from the rear side toward the front side to catch a sewing thread 168. As seen from the position of a user, the hook 172 is positioned in front of the wire 186 which cooperates with the hook 172 to sandwich the thread 168 therebetween. Therefore, the user is required to pull the thread 168 rearward as indicated at arrow YD. This is considerably difficult. If the user forcibly pulls the thread 168 in an erroneous direction such as in a downward or frontward direction, the hook 172 may even be damaged.